This invention relates to a joint of a playpen.
The most closely related reference is U.S. Pat. No. 5,211,498 issued to the present inventor on May 18, 1993. Such a joint makes it easy to collapse a playpen using such a joint. However, there are two problems to be overcome in such a joint. The first problem is that any child within may be hurt when the playpen is unintentionally collapsed as the joint can be easily pivoted. The second problem is that the rigidity of such a joint is not sufficient. This invention is intended to solve the above-mentioned problems.